No they cannot be repaired .. it means the special ferrous coating on the disk platter will no longer stay magnetised, so can't be trusted to register as a 0 or 1
As to whether it means you need to replace the drive .. nobody can answer that.
It may be that all bad sectors have been marked as not to be used, and no new damage will occur.
But in my experience, when hard drives start to fail, they normally get worse fairly quickly.
By far the most common damage occurs when the read/write head touches the platter during operation (usually by being knocked) scraping off some of the ferrous coating .. the problem then is that as hard drives are sealed units, you now have iron flakes flying around inside the drive causing more damage.
About the only advice anyone can give you is
a) don't move laptops whilst they're running (ie. drive spinning and read/write head not in parked position) unless you're very careful and make no sudden moves .. IMHO if they contain a HDD they shouldn't be called laptops/notebooks/netbooks .. more "portable desktops" .. only SSD's are immune to movement.
(YES, they really are that sensitive)
b) keep an eye on the figure of bad blocks .. if it appears to be rising for no apparent reason, get a new drive quickly
Obviously the above doesn't apply to SSD's .. they have their own distinct behaviour when failing depending on whether they support TRIM and wear leveling
